cpd_2022_energy/lib/main.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'result_model.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MultiProvider(
        providers: [
          ChangeNotifierProvider.value(
            value: ResultModel(),
          ),
        ],
        child: MaterialApp(
          title: 'Energy',
          home: MyCustomFormState(title: 'Energy'),
        ));
  }
}

class MyCustomFormState extends StatelessWidget with InputValidationMixin {
  final String title;

  MyCustomFormState({required this.title});

  final formGlobalKey = GlobalKey<FormState>();

  final _controllerStartHeight = TextEditingController();
  final _controllerEndHeight = TextEditingController();
  final _controllerStartSpeed = TextEditingController();
  final _controllerEndSpeed = TextEditingController();
  final _controllerWeight = TextEditingController();

  @override
  void dispose() {
    _controllerStartSpeed.dispose();
    _controllerEndSpeed.dispose();
    _controllerWeight.dispose();
  }

  void _changeJoule(BuildContext context) {
    Provider.of<ResultModel>(context, listen: false).changeJoule(
      double.parse(_controllerWeight.text),
      double.parse(_controllerStartSpeed.text),
      double.parse(_controllerEndSpeed.text),
      double.parse(_controllerStartHeight.text),
      double.parse(_controllerEndHeight.text),
    );
  }

  @override
  Widget build(BuildContext context) {
    double _joule = Provider.of<ResultModel>(context).getJoule;
    String _energyWater = Provider.of<ResultModel>(context).getWater;
    String _energyIron = Provider.of<ResultModel>(context).getIron;
    return Scaffold(
        appBar: AppBar(
          title: Text(title),
        ),
        body: Form(
          key: formGlobalKey,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              TextFormField(
                controller: _controllerStartHeight,
                decoration: const InputDecoration(
                    labelText: 'Start height',
                    hintText: 'Enter the height at the start (in meters)'),
                validator: (value) {
                  if (isInputValid(value.toString())) {
                    return 'Please enter a floating point number';
                  }
                },
              ),
              TextFormField(
                controller: _controllerEndHeight,
                decoration: const InputDecoration(
                    labelText: 'End height',
                    hintText: 'Enter the height at the end (in meters)'),
                validator: (value) {
                  if (isInputValid(value.toString())) {
                    return 'Please enter a floating point number';
                  }
                },
              ),
              TextFormField(
                controller: _controllerStartSpeed,
                decoration: const InputDecoration(
                    labelText: 'Start speed',
                    hintText: 'Enter the speed at the end (in m/s)'),
                validator: (value) {
                  if (isInputValid(value.toString())) {
                    return 'Please enter a floating point number';
                  }
                },
              ),
              TextFormField(
                controller: _controllerEndSpeed,
                decoration: const InputDecoration(
                    labelText: 'End speed',
                    hintText: 'Enter the speed at the end (in m/s)'),
                validator: (value) {
                  if (isInputValid(value.toString())) {
                    return 'Please enter a floating point number';
                  }
                },
              ),
              TextFormField(
                controller: _controllerWeight,
                decoration: const InputDecoration(
                    labelText: 'Weight',
                    hintText: 'Enter the weight of the object (in kg)'),
                validator: (value) {
                  if (isInputValid(value.toString())) {
                    return 'Please enter a floating point number';
                  }
                },
              ),
              Text('$_joule Joule \n'
                  '$_energyWater Liter Wasser können damit erhitzt werden \n'
                  '$_energyIron kg Eisen können damit zu glühen gebracht werden'),
              Padding(
                padding: const EdgeInsets.symmetric(vertical: 16.0),
                child: ElevatedButton(
                  onPressed: () => {
                    if (formGlobalKey.currentState!.validate()) {
                      formGlobalKey.currentState!.save()
                    },
                    _changeJoule(context),
                  },
                  child: const Text('Submit'),
                ),
              ),
            ],
          ),
        ));
  }
}

mixin InputValidationMixin {
  bool isInputValid(String value) => new RegExp(r'[0-9]+.?[0-9]*').hasMatch(value);
}